Technical Specifications

Small size.  The tail is only 5.5 cm (2.1″) across, and the total width from the tail to the nose cone is only 21 cm (8.2″). The marine-grade stainless steel mounting foot is only 21 mm (0.8″) square, which will only take up about the size of a postage stamp at the top of your mast.  The total height of the Wind Instrument on the Mounting Rod is 16.1 inches (41 cm).  Without the Mounting Rod, the Wind Instrument is just 7.5 inches tall (19 cm).  Note the small size compared to the usual horizontal structure — about the same as a handheld wind meter.

The weight of the next-generation SailTimer Wind Instrument™ is 257 grams (9.0 oz), and 319 grams (11.2 oz) with the Mounting Rod attached. The previous version was 304 grams, which feels the same. For a non-metric comparison, there are 16 ounces in a pound, so the Wind Instrument and Mounting rod are only 11.2/16 ounces = 0.7 pounds. So the Wind Instrument and Mounting Rod weigh 30% less than a pound of coffee.

Wind Speed:  The blades on the Wind Instrument are only a fraction of the size of the cups on the previous version of our wireless anemometer, at only 68 mm wide (just 2.67 inches).  They turn on a pair of miniature ball bearings in the lightest puff of air.  In strong winds, they can spin so fast they are a blur, but the magnetic sensor that measures the wind speed can pulse at up to 11,000 times per second.  To avoid the usual potentiometer and circuits that cannot get wet, we use an ingenious design with a tiny magnet on the base of the wind cups.  It triggers a magnetic sensor inside the tail of the wind direction arrow each time the cups rotate.  We can therefore completely seal the sensor in the tail.  Invisible magnetism reaches from the tiny magnet on the wind cups over to the tail of the wind direction arrow, and through the tail shell to the wind speed sensor.

Wind Direction is precisely monitored by a miniature digital compass and motion sensor right inside the wind direction arrow.  The same technology used in spacecraft and fighter jets.  This gives incredibly accurate wind direction, even when sailing along heeled over.  Our digital compass samples 25 times per second, which is presumably much faster than you need to get wind direction updates.  There is no dead zone at the end of the rotation, unlike the potentiometer that is used for wind direction in many masthead anemometers.  The arrow turns on a needle bearing with virtually no friction, in wind as light as 2 knots.  It is also perfectly balanced, so that it does not tilt down from gravity when you heel over.  With all of the electronics inside the tail, there is no wiring to chafe, break or short out.  Calibration is not needed, because the arrow knows what direction it is pointing.  The first anemometer that is easy to use with rotating masts.

Wireless transmissions
are via Bluetooth Low Energy (also called Bluetooth 4, or Bluetooth Smart).  Data is compliant with NMEA 0183, and is open for third-party apps and products to use.  (We also have the Air Link accessory, for converting to wifi or wiring in to NMEA 0183 networks for other marine electronics such as chartplotters.)  The typical keelboat mast is under 65 feet tall, and the Bluetooth transmissions are designed to exceed this, particularly with direct line of sight.  The Wind Instrument also includes signal strength in its data transmissions, so that you can evaluate the signal strength in real time while selecting a location for your receiving device.  The signal can generally pass through a bimini top or dodger unobstructed, although the cabin roof would typically reduce the signal strength (the same as wifi can only go through so many walls at home).  However, the signal may also be able to reflect off of hard surfaces in the cockpit to bounce through the companionway into the cabin.

Advanced Lithium Iron Phosphate batteries, for extra-long lifespan and operation in extreme temperature ranges.  Lithium Iron Phosphate (LFP) batteries are a new type of lithium-ion battery, with a longer cycle life than other lithium-ion batteries (and far longer than traditional lead-acid rechargeable batteries).  They also have better power density that other lithium-ion batteries, and better thermal and chemical stability for safety.

You may know that standard rechargeable NiMH and NiCd batteries cannot be charged in freezing temperatures, and have lower runtime and power output below freezing. (Non-rechargeable alkaline batteries too.)  But the battery in the SailTimer Wind Instrument™ can operate safely and reliably in a wider temperature range from near freezing to +85 degrees Celsius (185 degrees F). It has an advanced new chemistry designed for outdoor use.

The battery in the Wind Instrument also has an extremely slow self-discharge rate. When in storage it only loses about 1% per month. In comparison, NiMH can lose 20% of its charge the first day, and self-discharge 30% a month after that.  So if your model has an off-switch, you can easily put the Wind Instrument in storage for the winter, without it losing its charge or its settings. (Even if it was flat, the Wind Instrument will not lose its settings.)

Traditional rechargeable batteries like NiMH, NiCd and Lead-Acid contain toxic chemicals and heavy metals which are harmful to the environment, and require special disposal. But our lithium iron phosphate batteries contain no toxic chemicals or heavy metals, in compliance with the European Union’s Restriction of Hazardous Substances Directive.  They could be recycled where available, or are safe for displosal in normal municipal waste.

With that kind of battery performance and lifespan, the technology formats will likely be replaced before the battery is.  So this battery has been designed with long life and reliable all-weather encapsulation rather than getting into problems with replaceable batteries, waterproof gaskets, leaks, corrosion, condensation and short circuits.  It is maintenance-free.

Power consumption and solar charging:  We have developed one of the few wireless devices with the ability to be able to generate enough power for transmitting to smartphones and tablets from solar panels alone.  It never needs to be plugged in to recharge. The Wind Instrument transmits faster in newer models. Until Jan. 2021 the RB model the transmitted at 3 times per second, and the subsequent WMM model gives optional 5 or 10 times per second. Faster transmissions use more power, but we have developed a sophisticated power management system to achieve this…

When operating in direct sunlight, the Wind Instrument is so frugal that it only uses 2% of the power being generated by the solar panels, and does not need to draw from the battery at all.

The SailTimer Wind Instrument™ was designed so that even if you are doing a lot of night sailing on an extended expedition, you can generate more than enough power during daylight for unlimited around-the-clock operation.  If you ever needed the backup battery power (e.g. at dusk or in very gloomy fog), the battery has backup power for weeks of additional operation.

The Wind Instrument RB can be turned off for the off-season by unplugging the battery, which works well in Northern latitudes where sunlight may be limited during the winter. The lithium batteries only lose 1% power per month when in storage, so will still be at approximately the same level the following spring.

Solar charging varies with sun conditions, but on a cloudy day, it only takes 1 hour of solar charging to replace 16 hours of Wind Instrument usage while sailing.  And in direct sunlight, this goes up, so that it only takes 1 hour of solar charging to replace 35 hours of usage.  Pretty amazing.

Materials in the Wind Instrument were carefully chosen with the chafe and day-to-day wear & tear of sailing and tropical sun in mind.  Marine-grade stainless steel for the mounting rod and mounting accessories. The vertical Spindle and the Pivot Rod are the synthetic polymer “acetal” (polyoxymethylene or POM), which is a rigid material that is low friction and wear-resistant like nylon (but does not absorb moisture the way nylon does). The innovative encapsulation of the tail section is UV-resistant molded polyurethane, which is “water clear” to allow the sun’s rays through to the solar cells. The miniature bearings in the rotating parts are now premium Ceramic for the best performance and no corrosion.

Tripod mount on base
attaches to camera hand-grips, tripods, and all of the Go-Pro camera mounting accessories.  The Mounting Rod and black base of the Wind Instrument attach with a metric M6 thread.  To attach a 1/4-inch tripod screw to the Wind Instrument, we have a small adapter on the mounting accessories page that works with any tripod fitting.  Or, if you can put a different screw on your tripod fitting, you may be able to get a short M6 screw with a wide head from your local hardware store.  GoPro has lots of different fittings for hand-grips, rails, bikes, helmets, suction cups, clamps, bendable arms, stick-on bases, etc.  The Joby Gorillapod has 3 wrap-around legs to grab on to things for mounting or use as a tripod.  Obviously, no tools are required for mounting on any of these kinds of camera mounts.  They can also be quickly removed with a clip or a few easy turns, making the SailTimer Wind Instrument™ very portable.

Quick release mechanisms:
  The black base of the Wind Instrument is easily unscrewed from its stainless steel Mounting Rod by simply turning the locking nut, without needing to remove the 4 screws or nuts & bolts attaching the foot of the mounting rod to the masthead.  You could leave the Mounting Rod on the masthead year-round, even if you remove the Wind Instrument.  That is faster and easier, and keeps the nuts & bolts or screws tightly attached on the masthead.  If you like to remove the Wind Instrument from the mounting rod frequently, you can also replace the lock nut on the Mounting Rod with a metric M6 stainless steel wing-nut, for a quick release with no tools. The Wind Instrument also has an L-Bracket accessory with wing-nut hose clamps for easy attachment to a pole or stanchion temporarily or quick removal (no tools required).

The Owner’s Manual provides quick-start, operating and installation details.  Rather than printing a booklet for the box, we use a PDF in case details need to be updated in future. You can view the Owner’s Manual in your browser by clicking the following link, or right-click to save a copy:  Owner’s Manual PDF (4.7 MB).


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